Shock waves are propagating pressure pulses in elastic media, such as air, water and human/animal tissue. Acoustic shock waves have been used for various medical purposes as a noninvasive and non-surgical treatment. It has been proven to be effective to treat a variety of medical conditions in various clinical practices and research reports. For example, in urology, high-intensity focused shock waves are used for breaking kidney/bladder/urethra stones into small fragments on the order of several millimeters in diameter (i.e., lithotripsy), so that the small pieces can be transported out of the patient's body through the urethra. In orthopedics, shock waves are used for pain and inflammation relief/curing in joints and healing of bones. It is also shown that shock wave therapy is effective for healing wound, revascularization, and Peyronie's disease. In particular, it is shown that shock wave therapy is effective for revascularization, increasing blood flow in human tissue, and curing male erectile dysfunction (i.e., the inability or impaired ability to achieve a penile erection).
The erection of a penis requires sufficient arterial inflow into the two corpora cavernosa and corpus spongiosum (with the latter being relatively minor), so that they are engorged and enlarged. The expansion in volume of the corpora cavernosa and corpus spongiosum compresses the cross-section areas of veins within a penile shaft, which suppress the outflow of blood. Shock wave therapy for erectile dysfunction has been clinically shown to be effective by increasing the arterial blood flow and stimulate revascularization within the two corpora cavernosa. Note that the two corpora cavernosa not only exist in the penile shaft, but also exist in the penile crura/roots area. Moreover, the ischiocavernosus muscle, which stabilize the erect penis, and bulbospongiosus muscle, which also contribute to erection, also exist in the penile roots area. The coverage of both regions is necessary for optimized efficacy of the treatment.
Acoustic shock wave generation is often based on three different mechanisms: electrohydraulic, electromagnetic, and piezoelectric. In the electrohydraulic method, a pulse electric discharge between two closely positioned electrodes inside water induces a sudden vaporization of small amount of water nearby. This rapid increase of volume caused by the vaporization creates a pressure pulse in the water, thus generates radial propagating shock waves. In the electromagnetic method, an electric current pulse in a conductor coil results in a pulsed electromagnetic field, which in turn repels a conductive film having certain elastic properties and positioned closely to the coil, thereby generating a momentary (e.g., pulsed) displacement in the conductive film. The momentary displacements in turn generate shock waves with wave fronts parallel to the metal film surface. Alternatively, in the piezoelectric shock wave generation method, electrical voltage pulses are applied to an array of piezoelectric ceramic tiles. The voltage pulses induce volume expansions and contractions of the ceramics with each, thereby generating shock waves with wave fronts parallel to the ceramic surfaces.
In some devices and methods, shock waves originate from only a small area of the device and target one or more focal points or a focal volume (e.g., by utilizing an ellipsoidal or parabolic reflection surface to redirect the shock wave (e.g., generating directly from a partial spherical surface generator (electromagnetic or piezoelectric), or reflecting using a surface. Some of the discussed designs share a key feature that the shock wave transducers have a window through which shock waves are emitted, and this window is configured to transmit shock waves towards a specific direction regardless whether the shock waves are convergent or divergent. The shock wave energy exits the window and propagates away from the window towards the target. Using these shock wave devices requires an operator to hold the patient's penis with one hand, and to scan the shock wave generating head with the other hand along the length of the penis on both sides for the coverage of both corpora cavernosa. Furthermore, some of the discussed devices and methods do not contain the generated shock waves to a specific volume or cavity when treating a patient's penis. For example, FIG. 1A shows a focusing device with a point source (usually realized using electrohydraulic method) located in one focal point of an ellipsoid. The radial generated shock waves are reflected by the ellipsoidal surface and become focused on the other focal point of the ellipsoid outside an exit window of the generator. FIG. 1B shows a device for generating planar shock wave by reflecting the shock waves generated by a point source using a parabolic curved surface. By modifying the shape of the reflection surface or the shape of the surface generator, the shock wave emission can be changed from convergent to divergent. All the prior arts have a share feature, which is an exit window and a certain direction of transmission regardless of convergent, divergent, or planar.